This program grant is concerned with biochemical and biological aspects of perinatal life. It will emphasize three main biological areas: 1) cellular division and morphogenesis; 2) cellular differentiation and function; and 3) environmental effects on perinatal growth and differentiation. The primary objective is to study the effect of various environmental stimuli on different phases of intrauterine and extrauterine growth and to examine the ability of the organism to adapt to these influences. We have proposed specific model systems for investigation. Pyrimidine biosynthesis and the association of complex carbohydrates with cell surfaces will serve as indicators for study of the fundamental phenomena of cellular division and morphogenesis. Investigation of specific enzymes and complex proteins as well as their control systems will be used to provide information concerning the many biochemical changes in various organs that accompany cellular differentiation and function. Finally, the effect of foodstuffs and oxygen will be examined as examples of external environmental stimuli which affect the growth of fetus and infant. The methodology will be primarily biochemical and physiological with particular emphasis on time-dependent systems. We conceive that the various environments to which the growing organism is exposed, from fertilized egg to newborn child, will determine his biological capabilities as an adult. This investigative program is constructed to consider these various stages of the life cycle of man in relation to environmental stimuli.